Animal steroids are compounds that influence an animal’s bodily functions. Derived from cholesterol, these substances are naturally found in all animals, including humans, and are produced by organs like the adrenal cortex, ovaries, and testes. They act as chemical messengers, regulating biological processes such as growth, development, and reproduction. Steroids impact animal physiology, affecting systems from metabolism to the immune response, leading to both beneficial applications and potential concerns.
Types and Medical Applications
Steroids in veterinary medicine fall into two categories: anabolic steroids and corticosteroids. Anabolic steroids are synthetic versions of testosterone, designed to enhance tissue-building while minimizing masculinizing effects. These compounds promote protein synthesis, especially in muscle tissue, leading to increased muscle mass and improved appetite. Veterinarians prescribe anabolic steroids like stanozolol, boldenone, or nandrolone for various conditions:
Chronic wasting diseases
Severe parasitism leading to weight loss
Anemia associated with long-term illness
Recovery from severe injuries or surgeries
Support bone formation after orthopedic procedures
Corticosteroids are synthetic versions of hormones naturally produced by the adrenal glands, such as cortisol. They are used for their anti-inflammatory and immunosuppressive properties. Veterinarians use corticosteroids like prednisone, prednisolone, or dexamethasone to manage inflammatory conditions, including arthritis, skin allergies or asthma, and certain autoimmune diseases. They also treat some types of cancer or conditions like Addison’s disease, which involves insufficient adrenal hormone production.
Non-Medical Uses and Health Concerns
Beyond medical applications, steroids are sometimes used in animals for non-medical purposes. Anabolic steroids are illicitly used in livestock for growth promotion, increasing muscle mass and improving feed efficiency for economic gain. For instance, steroidal implants in beef cattle can increase average daily gain by approximately 21% and improve feed efficiency by about 11%, resulting in a 7% increase in carcass weight. These compounds are also misused in competitive animals, such as racing horses or show dogs, to enhance performance or appearance, providing an unfair competitive advantage.
The inappropriate or excessive use of steroids in animals can lead to health concerns.
Anabolic Steroid Risks
Anabolic steroids can cause liver and kidney damage, heart muscle degeneration, and an increased risk of muscle and tendon ruptures. Behavioral changes, such as increased aggression, irritability, and anxiety, have also been observed. In reproduction, anabolic steroids can lead to issues like testicular atrophy in males and abnormal sexual behavior or anestrus in females.
Corticosteroid Risks
Corticosteroid misuse can cause side effects such as increased thirst and urination, weight gain, muscle weakness, and a “pot-bellied” appearance. Long-term or high-dose corticosteroid use can also suppress the immune system, making animals more susceptible to infections. It can also lead to conditions like hyperglycemia, which increases the risk of diabetes, or osteoporosis, weakening bones.
Regulation and Human Safety
The use of steroids in animals, especially those intended for human consumption, is subject to regulations to protect public health. In the United States, the Food and Drug Administration (FDA) approves specific steroid hormone drugs for use in beef cattle and sheep to enhance growth rates. These approved substances include natural hormones like estrogen, progesterone, and testosterone, as well as synthetic versions such as trenbolone acetate and zeranol. The FDA mandates “withdrawal periods,” which specify the time between the last drug administration and when the animal can be slaughtered. This ensures drug residues in meat or dairy products fall below established safe levels. For most approved steroid implants, the withdrawal period is zero days, as the ears containing the implants are discarded.
Regulatory bodies conduct testing and monitoring programs to detect illegal steroid use or unsafe residue levels in the food supply. Samples of meat, milk, and animal tissues are routinely tested to ensure compliance with maximum residue limits (MRLs). The European Union, for example, banned the use of hormonal growth promoters in meat production since 1988 due to concerns about animal welfare and potential human health risks from residues. In competitive animal sports, anti-doping regulations maintain fair competition and safeguard animal welfare. Organizations like the Association of Racing Commissioners International (ARCI) and the International Federation for Equestrian Sports (FEI) maintain lists of prohibited substances, often exceeding 1,300 compounds, and conduct testing to detect their presence.